The present invention relates, in general, to methods and apparatus for controlling the movement of supportive wheeled vehicles of the type that ordinarily would be pushed or pulled by an operator, and, more particularly, to the application of such methods and apparatus to walking aids for weak but ambulatory people, for apparatus for adjusting such walking aids to meet the particular and evolving needs of such people, and more particularly to an improved electronically controlled braking system for such walking aids.
A wide range of structures have been devised to assist people who find it difficult to walk unaided, and who may be lacking in strength or manual dexterity. A commonly-used structure for this purpose is customarily referred to as a walker, although various other structures such as wheel chairs, carts and the like are also available. The present invention will be described in conjunction with walkers, but it will be understood that the invention is not limited to a particular assistance structure. Conventionally, a walker is fabricated from tubing, has three or four vertical legs and has at least a horizontal support bar or a pair of spaced handles that can be grasped by the user, and is light-weight enough to enable the ambulatory person to move it between steps. Prior such structures require the user to manually grasp the walker, lift it, and move it forward a desired distance. The user then walks behind the structure to a position of greater stability near it, and repeats the process.
In addition to providing a stable support for moving about, walkers are especially useful for ambulatory people who may have dizzy spells, for then the walker serves as a stable structure with which the person using the device may support himself or herself when needed. If the user stumbles, a fall may be avoided by quickly grasping the walker, and for these reasons, the stability of a walker is of utmost importance.
Walkers, as executed in the prior art, have some problems, however. A lightweight walker can be easy to lift, but because of its lightness, it may not be stable, whereas a heavy walker will be stable, but difficult to lift. The operation of lifting and moving a conventional walker can make locomotion difficult, awkward, and unstable for people who are too weak to firmly grasp or to lift it, for during the time that the walker is being lifted and moved, the user is less stable even than would ordinarily be the case when standing alone and without external support. Thus, the act of lifting the walker can be a source of difficulty for the user.
To overcome this problem, walkers have been designed with wheels, some with motor-driven wheels, which allow the user to move the walker without having to lift it. However, wheels make the walker essentially unstable.
This problem has been recognized, and attempts have been made to lend stability by providing manually actuatable, cable-operated hand brakes for the wheels on walkers. Again, however, the use of hand brakes presents its own problems, since the operator may be afflicted with arthritis or some other debilitating injury or illness which prevents or makes difficult the laborious operation of the brakes and maintenance of the steady pressure required to operate them. These hand brakes are also not well suited for one needing a steadying support after a sudden stumble, since at such times, when the user quickly reaches for the walker, he or she is unlikely to be able readily to grasp the hand brake, which may be far in front of the user, and may instead simply push the walker further away. Further, squeezing a brake may be uncomfortable or difficult to coordinate with the users attempts to maintain stability.
Attempts to improve the stability of walkers with wheels include the use of various spring-loaded braking arrangements such as the so-called glide brakes which gradually, although inefficiently, brake the walker when weight or downward pressure is applied. In such devices, wheels may be mounted on telescoping legs that are spring-biased to move the wheels into contact with the ground to provide mobility for the walker. When the operator leans on the walker, the operator's weight overcomes the spring bias to telescope the wheel, allowing the walker leg to gradually contact the ground and provide a brake. Unfortunately, however, most of the “downward” force applied to a walker in motion is, in reality, a forward force. Therefore, such arrangements can be hazardous to the operator, since they do not respond to users' needs at different times, and may not be responsive to the characteristics and abilities of a particular user, with the result that the walker can roll away from the operator if insufficient pressure is being applied, or may stop prematurely upon application of a light pressure. Many walkers use a combination of wheels and ground-engaging legs; for example, two legs at the rear of the walker and two wheels at the front, to prevent accidental rolling, but such walkers can be awkward to use, since they require some lifting and rolling at the same time.
Motorized walkers with motor driven wheels have been provided, and some walkers have a predetermined operation when switched on so that they will move only a preselected distance. However, such devices may be heavy, and not only energy inefficient, but may be dangerous to disabled people. Further, they may essentially remove control of operation from the operator and may, if accidentally activated, present additional danger to the operator.
A still further problem with prior walking aids is their inability to provide for differing and changing needs. Individual's needs evolve as their conditions improve or deteriorate, but prior walkers have not been able to accommodate to such changes. As a result, a walker that is initially suitable for an individual may gradually become unsuitable over a period of time, and may not be usable by another person, such as a friend or family member.
Electric brakes for walkers are described in general in U.S. Pat. Nos. 5,636,651, issued on 10 Jun. 1997 and 5,794,639, issued on 18 Aug. 1998, both to the applicant herein, the disclosures of which are hereby incorporated herein by reference. As there described, a typical walker includes a frame having a handle or handles that may be grasped by the user, and three or four support legs. To provide mobility for the user, a wheel is affixed to the bottom of each leg, and in accordance with the patents, at least two of the wheels are provided with electrically operated brakes responsive to a switch placed on one of the handles for activation by the user. As described, the walker may incorporate active braking, wherein the brakes are normally released but may be activated by the operator when needed, or may incorporate passive braking, wherein the brakes are normally engaged but may be released by the operator when the walker is to be moved.
The electrically controlled brakes of the foregoing patents are an improvement over prior walkers with mechanically operated brakes, for as discussed above, mechanical brakes may be difficult to operate for those having reduced strength in their hands or who have slowed reflexes, and may be hard to grip for operators having arthritis in their hands. Further, mechanical brakes are not a realistic option for those having severe impairment of the hands, or who may be missing a hand. Additionally, the prior walkers, whether having mechanical or electrical brakes, can be unstable when the operator tries to move from a sitting to a standing position, and can be hard to push when used on uphill inclines and may roll away from the user when used on downhill inclines.
Thus, there is a need for an improved system for controlling the motion of wheeled walkers that can be operated by the feeble or infirm and which can be easily, reliably, and selectively made stable or mobile, which can be adjusted to meet evolving or different needs, which will be safe for the user, and which will be easy to use, so as to enhance the mobility of the user under any conditions.